Exploring the best treatment options for BRAF-mutant metastatic colon cancer

Liver Transplantation for Nonresectable Colorectal Liver Metastases (CRLM)

Transplantation represents the most radical locoregional therapy through removal of the liver, associated vasculature and locoregional lymph nodes, and replacing it with an allograft. Recent evidence has demonstrated that transplantation for unresectable CRLM is feasible with acceptable post-transplant outcomes in a highly selected cohort of patients. Controversy exists regarding whether transplantation is an appropriate treatment for such patients, due to concerns regarding disease recurrence in the transplanted graft in an immunosuppressed recipient along with utilising a donor liver which are in short supply. Expanding the indications for liver transplantation may also limit access for other patients with end-stage liver disease having ethical implications due to the effect of increasing the waiting list. In this review, we summarise the current evidence for liver transplantation in patients with nonresectable CRLM and highlight unresolved controversies and future directions for this type of treatment.

Partial response to crizotinib + regorafenib + PD-1 inhibitor in a metastatic BRAF V600EMT colon cancer patient with acquired C-MET amplification and TPM4-ALK fusion: a case report

Background

Colorectal cancer (CRC) with the Raf murine sarcoma viral oncogene homolog B (BRAF) V600E had a relatively poor prognosis. Anaplastic lymphoma kinase (ALK) fusion and the mesenchymal-to-epithelial transition factor (MET) amplification have been recognized as potentially important therapeutic targets in non-small cell lung cancer (NSCLC). However, both of them are of extremely lower frequencies (<2%) in metastatic CRC, and few studies have mentioned the real application of their inhibitors in CRC treatment.

Case Description

A 49-year-old Chinese male was diagnosed with ascending colon adenocarcinoma (cT3N+?M1) with liver metastases. The patient performed next-generation sequencing (NGS) using tissue and circulating tumor DNA (ctDNA), and the results showed a BRAF V600E mutation. He received an initial combination treatment with cetuximab, dabrafenib, and trametinib with a partial response (PR) assessment. We changed the therapy regimen on this patient several times because of the patient's intolerance to the drugs or the inefficacy of the treatment. During this period, we detected the c-MET amplification and tropomyosin 4 (TPM4)-ALK fusion by NGS after triplet targeted therapy (tislelizumab, dabrafenib, and trametinib), thus he was finally treated with programmed cell death protein 1 (PD-1) inhibitor (tislelizumab), MET/ALK inhibitor (crizotinib) plus multikinase inhibitor (regorafenib). Imageological examinations showed that PR was achieved and ctDNA sequencing results indicated a significantly reduced BRAF mutation frequency, MET amplification and TPM4-ALK fusion were undetectable. NGS analysis of peripheral blood showed a recurrence of the MET acquired resistant amplification mutation over 2 months of ongoing treatment. but the patient was assessed as PR and still under treatment of crizotinib, tislelizumab and regorafenib within good physical condition. At the last follow-up on October 2021, the patient died of symptomatic treatment fail for obstructive jaundice. The patient finally achieved 11 months overall survival.

Conclusions

This study reported a co-existence of a BRAF V600E mutation, c-MET amplification and TPM4-ALK fusion in a CRC patient. Administration of crizotinib combined with regorafenib and tislelizumab obtained an obvious response. Furthermore, continuous ctDNA detection appears to be a promising technique to monitor tumor burden, which may provide better clinical decision support during the disease course.

The importance of protein domain mutations in cancer therapy

Cancer is a complex disease that is caused by multiple genetic factors. Researchers have been studying protein domain mutations to understand how they affect the progression and treatment of cancer. These mutations can significantly impact the development and spread of cancer by changing the protein structure, function, and signalling pathways. As a result, there is a growing interest in how these mutations can be used as prognostic indicators for cancer prognosis. Recent studies have shown that protein domain mutations can provide valuable information about the severity of the disease and the patient's response to treatment. They may also be used to predict the response and resistance to targeted therapy in cancer treatment. The clinical implications of protein domain mutations in cancer are significant, and they are regarded as essential biomarkers in oncology. However, additional techniques and approaches are required to characterize changes in protein domains and predict their functional effects. Machine learning and other computational tools offer promising solutions to this challenge, enabling the prediction of the impact of mutations on protein structure and function. Such predictions can aid in the clinical interpretation of genetic information. Furthermore, the development of genome editing tools like CRISPR/Cas9 has made it possible to validate the functional significance of mutants more efficiently and accurately. In conclusion, protein domain mutations hold great promise as prognostic and predictive biomarkers in cancer. Overall, considerable research is still needed to better define genetic and molecular heterogeneity and to resolve the challenges that remain, so that their full potential can be realized.

CXCL16 promotes tumor metastasis by regulating angiogenesis in the tumor micro-environment of BRAF V600E mutant colorectal cancer

Patients of colorectal cancer (CRC) with BRAF V600E mutation obtain poor prognosis. This study aimed to explore the role and mechanism of BRAF V600E mutation in angiogenesis of tumor micro-environment (TME). It has been reported that CXCL16 expression in TME is closely related to BRAF mutation. Clinicopathological features of CRC with BRAF V600E mutant or wild type were collected in this study. Immunohistochemistry (IHC) assays were conducted to test the expressions of vascular endothelial growth factor (VEGF), CD31 and CXCL16. ROC curve was used to determine the optimal cut off values of CXCL16. A total of 680 patients including 141 BRAF V600E type and 679 wild type were included. BRAF V600E mutant tumors were presented with significant worse clinicopathological features and a shorter overall survival (OS) than wild-type. Besides, chemokines CXCL16 was up-regulated in BRAF V600E mutant tissues and was associated with poorer prognosis. In addition, VEGF levels and vascular endothelial cell density was significantly increased in BRAF mutation. At last, CXCL16 was positively correlated with VEGF expression and vascular endothelial cell density. In conclusion, BRAF V600E mutations may promote metastasis of CRC by regulating CXCL16 expression and promoting angiogenesis in the TME.

Pin1 inhibitor API-1 sensitizes BRAF-mutant thyroid cancers to BRAF inhibitors by attenuating HER3-mediated feedback activation of MAPK/ERK and PI3K/AKT pathways

BRAFV600E mutation is one of the most therapeutic targets in thyroid cancers. However, its specific inhibitors have shown little clinical benefit because they can reactivate the MAPK/ERK and PI3K/AKT pathways by feedback upregulating the transcription of HER3. Peptidyl-prolyl cis/trans isomerase Pin1 has been proven to be closely associated with tumor progression. Here, we aimed to determine antitumor activity of Pin1 inhibitor API-1 in thyroid cancer and its effect on cellular response to BRAF inhibitors. The results showed that API-1 exhibited strong antitumor activity against thyroid cancer. Meanwhile, it improved the response of BRAF-mutant thyroid cancer cells to BRAF inhibitor PLX4032 and there was a synergistic effect between them. Specially, a combination therapy of API-1 and PLX4032 significantly inhibited cell proliferation, colony formation, and the growth of xenograft tumors as well as induced cell apoptosis in BRAF-mutant thyroid cancer cells compared with API-1 or PLX4032 monotherapy. Similar results were also observed in transgenic mice with BrafV600E-driven thyroid cancer. Mechanistically, API-1 enhanced XPO5 ability to export pre-microRNA 20a (pre-miR-20a) from the nucleus to cytoplasm, thereby promoting the maturation of miR-20a-5p. Further studies showed that miR-20a-5p specifically targeted and down-regulated HER3, thereby blocking the reactivation of MAPK/ERK and PI3K/AKT signaling pathways caused by PLX4032. These results, taken together, demonstrate that Pin1 inhibitor API-1 significantly improves the sensitivity of BRAF-mutant thyroid cancer cells to PLX4032. Thus, this study not only determines the potential antitumor activity of Pin1 inhibitor API-1 in thyroid cancer but also offers an alternative therapeutic strategy for BRAF-mutant thyroid cancers by a combination of Pin1 inhibitor and BRAF kinase inhibitor.

BRAFV600E Metastatic Colorectal Cancer: Perspective from a Patient, a Caregiver, and an Oncologist

This article has been co-authored by a patient with right-sided BRAFV600E metastatic colorectal cancer (mCRC), his caregiver, and an oncologist. Here the patient and caregiver discuss their personal experiences struggling with cancer, including their fears, expectations, and attitudes as the disease progresses. The oncologist describes how patients with BRAFV600E mCRC are treated and how the management strategy can be balanced to mitigate any side effects. Improved diagnostic techniques and the availability of numerous treatment options, including various chemotherapy schemes and molecular-targeted drugs, can aid rapid implementation of treatment algorithms. The pivotal roles of patients' associations in the general support of patients and those close to them, and in facilitating the link with healthcare professionals, are highlighted in this perspective piece.

Bioinformatics and Expression Analyses of miR-639, miR-641, miR-1915-3p and miR-3613-3p in Colorectal Cancer Pathogenesis

Objectives: MicroRNAs (miRNAs) have important function in cancer development and progression. This study aims to determine the expression levels of miR-639, miR-641, miR-1915-3p, and miR-3613-3p in tissues of colorectal cancer (CRC) patients and the role of these miRNAs in the CRC pathogenesis. Methods: Tumor and non-tumor tissues were collected from a total of 59 CRC patients. qRT-PCR was used to identify the expressions of miR-639, miR-641, miR-1915-3p and miR-3613-3p. Through bioinformatics analysis, the target genes of miRNAs were identified by using DIANA mirPath v.3. Signaling pathways were generated using KEGG pathway database. Biological pathway, cellular component analysis, and analysis of Protein-Protein Interactions (PPI) Networks were performed using FunRich and STRING database. Results: Our findings revealed that miR-639, miR-641 and miR-3613-3p were significantly downregulated, and miR-1915-3p was significantly upregulated in tumor tissues compared to non-tumor tissues (p˂0.05). Furthermore, MAPK signaling pathway was the most enriched KEGG pathway regulated by miR-639, miR-641, miR-1915-3p and miR-3613-p. According to the FunRich, it was demonstrated that the targeted genes by miRNAs related to the cellular component and biological pathways such as beta-catenin-TCF7L2, axin-APC-beta-catenin-GSK3B complexes, Arf6 signaling, Class I PI3K signaling, etc. And, by the PPI analysis, it was established that the target genes were clustered on CTNNB1 and KRAS. Conclusions: These outcomes imply that miR-639, miR-641 and miR-3613-3p have tumor suppressor roles, while miR-1915-3p has an oncogenic role in the pathogenesis of CRC. According to the results of the current study, dysregulated miR-639, miR-641, miR-1915-3p, and miR-3613-3p might contribute to the development of CRC.

The role of heavy metals in the development of colorectal cancer

OBJECTIVE

To investigate the relationship among 18 heavy metals, microsatellite instability (MSI) status, ERCC1, XRCC1 (rs25487), BRAF V600E and 5 tumor markers and their role in the development of colorectal cancer (CRC).

METHODS

A total of 101 CRC patients and 60 healthy controls were recruited in the present study. The levels of 18 heavy metals were measured by ICP-MS. MSI status and the genetic polymorphism were determined by PCR (FP205-02, Tiangen Biochemical Technology Co., Ltd., Beijing, China) and Sanger sequencing. Spearman's rank correlation was used to analyze the relationship among various factors.

RESULTS

The level of selenium (Se) was lower in the CRC group compared with the control group (p < 0.01), while vanadium (V), arsenic (As), tin (Sn), barium (Ba) and lead (Pb) were higher (p < 0.05), chromium (Cr) and copper (Cu) were significantly higher (p < 0.0001) in the CRC group than those in the control group. Multivariate logistic regression analysis indicated that Cr, Cu, As and Ba were the risk factors for CRC. In addition, CRC was positively correlated with V, Cr, Cu, As, Sn, Ba and Pb, but negatively correlated with Se. MSI was positively correlated with BRAF V600E, but negatively correlated with ERCC1. BRAF V600E was positively correlated with antimony (Sb), thallium (Tl), CA19-9, NSE, AFP and CK19. XRCC1 (rs25487) was found to be positively correlated with Se but negatively correlated with Co. The levels of Sb and Tl were significantly higher in the BRAF V600E positive group compared to the negative group. The mRNA expression level of ERCC1 was significantly higher (P = 0.035) in MSS compared to MSI. And there was a significant correlation between XRCC1 (rs25487) polymorphism and MSI status (P<0.05).

CONCLUSION

The results showed that low level of Se and high levels of V, As, Sn, Ba, Pb, Cr, and Cu increased the risk of CRC. Sb and Tl may cause BRAF V600E mutations, leading to MSI. XRCC1 (rs25487) was positively correlated with Se but negatively correlated with Co. The expression of ERCC1 may be related to MSS, while the XRCC1 (rs25487) polymorphism is related to MSI.

New Ruthenium-Cyclopentadienyl Complexes Affect Colorectal Cancer Hallmarks Showing High Therapeutic Potential

Colorectal cancer (CRC) is among the most deadly cancers worldwide. Current therapeutic strategies have low success rates and several side effects. This relevant clinical problem requires the discovery of new and more effective therapeutic alternatives. Ruthenium drugs have arisen as one of the most promising metallodrugs, due to their high selectivity to cancer cells. In this work we studied, for the first time, the anticancer properties and mechanisms of action of four lead Ru-cyclopentadienyl compounds, namely PMC79, PMC78, LCR134 and LCR220, in two CRC-derived cell lines (SW480 and RKO). Biological assays were performed on these CRC cell lines to evaluate cellular distribution, colony formation, cell cycle, proliferation, apoptosis, and motility, as well as cytoskeleton and mitochondrial alterations. Our results show that all the compounds displayed high bioactivity and selectivity, as shown by low half-maximal inhibitory concentrations (IC₅₀) against CRC cells. We observed that all the Ru compounds have different intracellular distributions. In addition, they inhibit to a high extent the proliferation of CRC cells by decreasing clonogenic ability and inducing cell cycle arrest. PMC79, LCR134, and LCR220 also induce apoptosis, increase the levels of reactive oxygen species, lead to mitochondrial dysfunction, induce actin cytoskeleton alterations, and inhibit cellular motility. A proteomic study revealed that these compounds cause modifications in several cellular proteins associated with the phenotypic alterations observed. Overall, we demonstrate that Ru compounds, especially PMC79 and LCR220, display promising anticancer activity in CRC cells with a high potential to be used as new metallodrugs for CRC therapy.

Nursing care and management of adverse events for patients with BRAFV600E-mutant metastatic colorectal cancer receiving encorafenib in combination with cetuximab: a review

Encorafenib is a B-Raf proto-oncogene serine/threonine-protein kinase (BRAF) inhibitor, approved in the EU and USA, in combination with the epidermal growth factor receptor (EGFR) inhibitor cetuximab, for the treatment of patients with BRAF^V600E-mutant metastatic colorectal cancer (mCRC). In the pivotal BEACON CRC trial, patients achieved longer survival with encorafenib in combination with cetuximab vs. conventional chemotherapy. This targeted therapy regimen is also generally better tolerated than cytotoxic treatments. However, patients may present with adverse events unique to the regimen and characteristic of BRAF and EGFR inhibitors, which produce their own set of challenges. Nurses play an essential role in navigating the care of patients with BRAF^V600E-mutant mCRC and managing adverse events that patients may experience. This includes early and efficient identification of treatment-related adverse events, subsequent management of adverse events and education of patients and their caregivers around key adverse events. This manuscript aims to provide support to nurses managing patients with BRAF^V600E-mutant mCRC receiving encorafenib in combination with cetuximab, by summarising potential adverse events and providing guidance on how to manage them. Special attention will be paid to the presentation of key adverse events, dose modifications that may be required, practical recommendations and supportive care measures.

Adverse Events Associated with Encorafenib Plus Cetuximab in Patients with BRAFV600E-mutant Metastatic Colorectal Cancer: An in-depth Analysis of the BEACON CRC Study

BACKGROUND

The BRAF inhibitor encorafenib in combination with cetuximab was recently approved for patients with BRAF^V600E-mutated (BRAF^V600Emut) metastatic colorectal cancer (mCRC). Approval was based on positive results from the phase 3 BEACON CRC study in BRAF^V600Emut mCRC patients who had progressed after 1-2 previous regimens. This analysis provides a detailed examination of the adverse events (AEs) of interest (AEIs) with encorafenib+cetuximab in the BEACON study to aid gastrointestinal oncologists, given the limited experience with this combination.

MATERIALS AND METHODS

AEIs, including dermatological AEs, arthralgia/myalgia, nausea/vomiting, diarrhea, abdominal pain, fatigue/asthenia and nephrotoxicity, were examined in the doublet therapy group. Clinical characteristics associated with these AEs, AE grade, time to onset and time to resolution were also studied.

RESULTS

Safety analysis included 216/220 patients randomized to doublet therapy. The most commonly occurring AEI was dermatological toxicity (75.5%), followed by arthralgia/myalgia (56.0%) and fatigue/asthenia (56.0%). Other than nephrotoxicity (7 patients; 5/7 with Grade 3 or 4), most AEs were Grade 1 or 2. Most AEs were more common in women than men (nausea/vomiting, diarrhea, abdominal pain, dermatological AEs, and arthralgia/myalgia). Nausea/vomiting, abdominal pain and fatigue/asthenia were more common in patients aged ≥70 years. Most AEs developed early, within the first 1-2 months of treatment, and resolved within 1-2 weeks. In addition, survival outcomes were better in patients experiencing arthralgia/myalgia or dermatological toxicities.

CONCLUSION

This analysis indicated that, except for rare cases of nephrotoxicity, encorafenib+cetuximab is well tolerated in most patients, with most AEIs being mild-to-moderate in severity, occurring early and resolving rapidly.

CLINICAL TRIAL REGISTRATION

the BEACON study (ClinicalTrials.gov, NCT02928224; EudraCT, 2015-005805-35).

Mapping Immune Correlates and Surfaceome Genes in BRAF Mutated Colorectal Cancers

Despite the impressive results obtained with immunotherapy in several cancer types, a significant fraction of patients remains unresponsive to these treatments. In colorectal cancer (CRC), B-RafV600 mutations have been identified in 8–15% of the patients. In this work we interrogated a public dataset to explore the surfaceome of these tumors and found that several genes, such as GP2, CLDN18, AQP5, TM4SF4, NTSR1, VNN1, and CD109, were upregulated. By performing gene set enrichment analysis, we also identified a striking upregulation of genes (CD74, LAG3, HLA-DQB1, HLA-DRB5, HLA-DMA, HLA-DMB, HLA-DPB1, HLA-DRA, HLA-DOA, FCGR2B, HLA-DQA1, HLA-DRB1, and HLA-DPA1) associated with antigen processing and presentation via MHC class II. Likewise, we found a strong correlation between PD1 and PD(L)1 expression and the presence of genes encoding for proteins involved in antigen presentation such as CD74, HLA-DPA1, and LAG3. Furthermore, a similar association was observed for the presence of dendritic cells and macrophages. Finally, a low but positive relationship was observed between tumor mutational burden and neoantigen load. Our findings support the idea that a therapeutic strategy based on the targeting of PD(L)1 together with other receptors also involved in immuno-modulation, such as LAG3, could help to improve current treatments against BRAF-mutated CRC tumors.

Targeting BRAF V600E in metastatic colorectal cancer: where are we today?

Colorectal cancer (CRC) is the second most frequent cause of direct cancer death worldwide. The study of the molecular state of oncogenes has predictive and prognostic value in metastatic CRC (mCRC). The B-raf proto-oncogene (BRAF) gene mutation represents the 8%-12% of all mutations in mCRC. The BRAF V600E mutation, considered the most common alteration of BRAF, corresponds to a constitutive kinase with a high activating capacity of the RAS/RAF/MEK/ERK pathway after a cascade of successive phosphorylations in the transcription of genes. BRAF V600E mutation is more prevalent in women, elderly, right-sided colon cancer and Caucasian population. Unfortunately, it is considered a poor predictive and prognosis biomarker. Patients with mCRC BRAF V600E mutated (BRAFm) are generally associated with poor response to chemotherapy and short progression-free survival and overall survival. Recently, randomised clinical trials have studied the combination of different chemotherapy regimens with angiogenic inhibitors in mCRC BRAFm. In addition, new anti-BRAF and immunotherapy agents have also been studied in this population, with positive results. The objective of this review is to acknowledge the biology and molecular pathway of BRAF, critically analyse the clinical trials and the therapy options published until today and evaluate the options of treatment according to the patient's clinical presentation.

Real-world first-line treatment of patients with BRAFV600E-mutant metastatic colorectal cancer: the CAPSTAN CRC study

BACKGROUND

BRAFV600E mutations occur in 8%-12% of metastatic colorectal cancer (mCRC) cases and are associated with poor survival. European guidelines recommend combination (doublet or triplet) chemotherapy plus bevacizumab in first line. However, an unmet need remains for more effective treatments for these patients.

PATIENTS AND METHODS

CAPSTAN CRC is a European, retrospective, multicenter, observational study evaluating real-world treatment practices for patients with BRAFV600E-mutant mCRC treated between 1 January 2016 and 31 January 2020. The primary objective was to describe first-line treatment patterns. Secondary objectives included describing baseline demographics, mutational testing procedures, treatment effectiveness, and safety.

RESULTS

In total, 255 patients (median age 66.0 years; 58.4% female) with BRAFV600E-mutant unresectable mCRC from seven countries were included. Most had right-sided tumors (52.5%) and presented with synchronous disease at diagnosis (66.4%). Chemotherapy plus targeted therapy (68.7%) was preferred at first line over chemotherapy alone (31.3%). The main first-line treatments were FOLFOX plus bevacizumab (27.1%) and FOLFOXIRI (folinic acid, 5-fluorouracil, oxaliplatin, irinotecan) with/without bevacizumab (27.1%/19.2%). Median duration of first-line treatment was 4.9 months. Overall, 52.5% received second-line treatment. Across all first-line regimens, progression-free survival (PFS) and overall survival were 6.0 [95% confidence interval (CI) 5.3-6.7] months and 12.9 (95% CI 11.6-14.1) months, respectively. Triplet plus targeted therapy was associated with more adverse events (75.0%) compared with triplet chemotherapy alone (50.0%) and doublet chemotherapy alone (36.1%). Multivariate analysis identified low body mass index and presence of three or more metastatic sites as significant prognostic factors for PFS.

CONCLUSIONS

This study is, to date, the largest real-world analysis of patients with BRAFV600E-mutant mCRC, providing valuable insights into routine first-line treatment practices for these patients. The data highlight the intrinsic aggressiveness of this disease subgroup, confirming results from previous real-world studies and clinical trials, and stressing the urgent need for more effective treatment options in this setting.

A self-guidance biological hybrid drug delivery system driven by anaerobes to inhibit the proliferation and metastasis of colon cancer

Colorectal cancer is often accompanied by multiple organ metastasis. Anaerobic Bifidobacterium Infantis (BI) bacterial can selectively grow in hypoxic colorectal tumor microenvironment (TME), to own the natural advantage of preferentially colorectal tumor targeting. Herein, a self-guidance biological hybrid drug delivery system (BI-ES-FeAlg/DOX) based on BI was constructed to inhibit the proliferation and metastasis of colon cancer. Results demonstrated that BI-ES-FeAlg/DOX could overcome physical barriers to target and accumulate in colon tumor tissues. Then DOX was released to kill tumor cells along with the phase transition (solid to liquid) of FeAlg hydrogel, due to Fe³⁺ was reduced to Fe²⁺by intracellular GSH. Meanwhile, BI-ES selectively colonized into tumors and expressed endostatin (ES) protein to down-regulate VEGF and bFGF expression, exerting anti-angiogenic effect. Moreover, FeAlg catalyzed H₂O₂ in the local tumor to generate cytotoxic ·OH, further enhancing the antitumor effect. The pharmacodynamic result in AOM/DSS model proved that BI-ES-FeAlg/DOX had the best therapeutic effect, with the final V/V₀ of 2.19 ± 0.57, which was significantly lower than the other groups. Meanwhile, on CT-26 tumor-bearing model, it also showed an outstanding anti-tumor effect with inhibition rate of 82.12% ± 3.08%. In addition, lung metastases decreased significantly in tumor metastasis model after BI-ES-FeAlg/DOX treatment.

Biomarkers in Metastatic Colorectal Cancer: Status Quo and Future Perspective

Colorectal cancer (CRC) is the third most frequent cancer worldwide, and its incidence is steadily increasing. During the last two decades, a tremendous improvement in outcome has been achieved, mainly due to the introduction of novel drugs, targeted treatment, immune checkpoint inhibitors (CPIs) and biomarker-driven patient selection. Moreover, progress in molecular diagnostics but also improvement in surgical techniques and local ablative treatments significantly contributed to this success. However, novel therapeutic approaches are needed to further improve outcome in patients diagnosed with metastatic CRC. Besides the established biomarkers for mCRC, such as microsatellite instability (MSI) or mismatch repair deficiency (dMMR), RAS/BRAF, sidedness and HER2 amplification, new biomarkers have to be identified to better select patients who derive the most benefit from a specific treatment. In this review, we provide an overview about therapeutic relevant and established biomarkers but also shed light on potential promising markers that may help us to better tailor therapy to the individual mCRC patient in the near future.

Application of histology-agnostic treatments in metastatic colorectal cancer

Cancer treatment is increasingly focused on targeting molecular alterations identified across different tumor histologies. While some oncogenic drivers such as microsatellite instability (MSI) and NTRK fusions are actionable with the very same approach regardless of tumor type ("histology-agnostic"), others require histology-specific therapeutic adjustment ("histology-tuned") by means of adopting specific inhibitors and ad hoc combinations. Among histology-agnostic therapies, pembrolizumab or dostarlimab demonstrated comparable activity in MSI metastatic colorectal cancer (mCRC) as in other tumors with MSI status (ORR 38% vs 40% and 36% vs 39%, respectively), while entrectinib or larotrectinib proved effective in NTRK rearranged mCRC even though less dramatically than in the overall population (ORR 20% vs 57%, and 50% vs 78%, respectively). Histology-tuned approaches in mCRC are those targeting BRAF^V600E mutations and ERBB2 amplification, highlighting the need of simultaneous anti-EGFR blockade or careful choice of companion inhibitors in this tumor type. Anti-RET and anti-ALK therapies emerged as a potential histology-agnostic indications, while anti-KRAS^G12C strategies could develop as future histology-tuned therapies. Targeting of ERBB2 mutations and NRG1 fusion provided discrepant results. In conclusion, agnostic targets such as MSI and NTRK fusions are already exploitable in mCRC, while the plethora of emerging histology-tuned targets represent a challenging opportunity requiring concurrent evolution of molecular diagnostic tools.

Learn to Estimate Genetic Mutation and Microsatellite Instability with Histopathology H&E Slides in Colon Carcinoma

Colorectal cancer is one of the most common malignancies and the third leading cause of cancer-related mortality worldwide. Identifying KRAS, NRAS, and BRAF mutations and estimating MSI status is closely related to the individualized therapeutic judgment and oncologic prognosis of CRC patients. In this study, we introduce a cascaded network framework with an average voting ensemble strategy to sequentially identify the tumor regions and predict gene mutations & MSI status from whole-slide H&E images. Experiments on a colorectal cancer dataset indicate that the proposed method can achieve higher fidelity in both gene mutation prediction and MSI status estimation. In the testing set, our method achieves 0.792, 0.886, 0.897, and 0.764 AUCs for KRAS, NRAS, BRAF, and MSI, respectively. The results suggest that the deep convolutional networks have the potential to provide diagnostic insight and clinical guidance directly from pathological H&E slides.

Prognostic and predictive molecular biomarkers in advanced colorectal cancer

The revolution of precision medicine has produced unprecedented seismic shifts in the treatment paradigm of advanced cancers. Among the major killers, colorectal cancer (CRC) is far behind the others. In fact, the great successes obtained in breast, NSCLC, melanoma, and genitourinary tract tumors have been observed only in fewer than 5 % metastatic colorectal cancer (mCRC): those with the mismatch repair deficiency (dMMR), a well-known predictive factor for to the outstanding efficacy of checkpoint inhibitors (CPI). The treatment of the remaining vast majority mCRC patients is still based upon only two molecular determinants: the RAS and BRAF mutational status. New promising biomarkers include HER2, tumor mutational burden (TMB) for its possible implications on CPI efficacy, and the extremely rare NTRK fusions. The Consensus Molecular Subtypes classification (CMS) is a good example of the efforts to combine different molecular features of this disease, although its relevance in clinical practice is still under investigation. In this Review, we focus on all these prognostic and predictive biomarkers, analyzing data from the most important clinical trials of the last years. We also try to rank them according to their prognostic and predictive power.

New Potential Immune Biomarkers in the Era of Precision Medicine: Lights and Shadows in Colorectal Cancer

Genetic alterations in CRC have shown a negative predictive and prognostic role in specific target therapies. The onset of immunotherapy has also undergone remarkable therapeutic innovation, although limited to a small subgroup of patients, the MSI-H/dMMR, which represents only 5% of CRC. Research is moving forward to identify whether other biomarkers can predict response to ICIs, despite various limitations regarding expression and identification methods. For this purpose, TMB, LAG3, and PD-L1 expression have been retrospectively evaluated in several solid tumors establishing the rationale to design clinical trials with concurrent inhibition of LAG3 and PD-1 results in a significant advantage in PFS and OS in advanced melanoma patients. Based on these data, there are clinical trials ongoing in the CRC as well. This review aims to highlight what is already known about genetic mutations and genomic alterations in CRC, their inhibition with targeted therapies and immune checkpoints inhibitors, and new findings useful to future treatment strategies.

Targeting the lncRNA FGD5-AS1/miR-497-5p/PD-L1 Axis Inhibits Malignant Phenotypes in Colon Cancer (CC)

Long noncoding RNAs (lncRNAs) regulate cancer progression and drug resistance. However, the role of lncRNA FGD5-AS1 in regulating colon cancer (CC) progression is still largely unknown. Hence, this study investigated the role of lncRNA FGD5-AS1 in regulating colon cancer (CC) progression and found that lncRNA FGD5-AS1 regulated miR-497-5p/PD-L1 axis to promote cancer progression in CC cells in vitro and in vivo. Specifically, we found that lncRNA FGD5-AS1 and PD-L1 tended to be high-expressed, while miR-497-5p was low-expressed in CC tissues and cell lines compared to the normal adjacent tissues and cells. Next, we found that lncRNA FGD5-AS1 positively regulated PD-L1 in CC cells by sponging miR-497-5p. Finally, our gain- and loss-of-function experiments evidenced that the lncRNA FGD5-AS1/miR-497-5p/PD-L1 axis regulates CC progression. Functionally, the data suggested that lncRNA FGD5-AS1 positively regulated while miR-497-5p negatively modulated malignant phenotypes, including cell proliferation, viability, invasion, migration, epithelial-mesenchymal transition (EMT), and tumorigenesis in CC cells. Interestingly, the inhibiting effects of lncRNA FGD5-AS1 ablation on CC development were abrogated by both silencing miR-497-5p and upregulating PD-L1. This study found that lncRNA FGD5-AS1 sponged miR-497-5p to upregulate PD-L1, resulting in CC progression, and provided novel agents for CC diagnosis and prognosis.

Ruthenium(II)-Cyclopentadienyl-Derived Complexes as New Emerging Anti-Colorectal Cancer Drugs

Colorectal cancer (CRC) is one of the most common malignancies and one of the leading causes of cancer-related death worldwide, urging the need for new and more efficient therapeutic approaches. Ruthenium complexes have emerged as attractive alternatives to traditional platinum-based compounds in the treatment of CRC. This work aims to evaluate anti-CRC properties, as well as to identify the mechanisms of action of ruthenium complexes with the general formula [Ru(η⁵-C₅H₄R)(PPh₃)(4,4′-R′-2,2′-bipyridine)][CF₃SO₃], where R = CH₃, CHO or CH₂OH and R′ = H, CH₃, CH₂OH, or dibiotin ester. The complexes (Ru 1–7) displayed high bioactivity, as shown by low IC₅₀ concentrations against CRC cells, namely, RKO and SW480. Four of the most promising ruthenium complexes (Ru 2, 5–7) were phenotypically characterized and were shown to inhibit cell viability by decreasing cell proliferation, inducing cell cycle arrest, and increasing apoptosis. These findings were in accordance with the inhibition of MEK/ERK and PI3K/AKT signaling pathways. Ruthenium complexes also led to a decrease in cellular clonogenic ability and cell migration, which was associated with the disruption of F-actin cytoskeleton integrity. Here, we demonstrated that ruthenium complexes, especially Ru7, have a high anticancer effect against CRC cells and are promising drugs to be used as a new therapeutical strategy for CRC treatment.

Encorafenib plus cetuximab with or without binimetinib in patients with BRAF V600E-mutated metastatic colorectal cancer: real-life data from an Italian multicenter experience

Background

Encorafenib plus cetuximab with or without binimetinib showed increased objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) compared with chemotherapy plus anti-EGFR in previously treated patients with BRAF V600E-mutated (mut) metastatic colorectal cancer (mCRC). Although no formal comparison was planned, addition of binimetinib to encorafenib plus cetuximab did not provide significant efficacy advantage.

Patients and methods

This real-life study was aimed at evaluating safety, activity, and efficacy of encorafenib plus cetuximab with or without binimetinib in patients with BRAF V600E-mut mCRC treated at 21 Italian centers within a nominal use program launched in May 2019.

Results

Out of 133 patients included, 97 (73%) received encorafenib plus cetuximab (targeted doublet) and 36 (27%) the same therapy plus binimetinib (targeted triplet). Most patients had Eastern Cooperative Group Performance Status (ECOG-PS) of 0 or 1 (86%), right-sided primary tumor (69%), and synchronous disease (66%). Twenty (15%) tumors were DNA mismatch repair deficiency (dMMR)/microsatellite instability (MSI)-high. As many as 44 (34%) patients had received two or more prior lines of therapy, 122 (92%) were previously exposed to oxaliplatin, and 109 (82%) to anti-vascular endothelial growth factor (anti-VEGF). Most frequent adverse events were asthenia (62%) and anti-EGFR-related skin rash (52%). Any grade nausea (P = 0.03), vomiting (P = 0.04), and diarrhea (P = 0.07) were more frequent with the triplet therapy, while melanocytic nevi were less common (P = 0.06). Overall, ORR and disease control rate (DCR) were 23% and 69%, respectively, with numerically higher rates in the triplet group (ORR 31% versus 17%, P = 0.12; DCR 78% versus 65%, P = 0.23). Median PFS and OS were 4.5 and 7.2 months, respectively. Worse ECOG-PS, peritoneal metastases, and more than one prior treatment were independent poor prognostic factors for PFS and OS. Clonality of BRAF mutation measured as adjusted mutant allele fraction in tumor tissue was not associated with clinical outcome.

Conclusions

Our real-life data are consistent with those from the BEACON trial in terms of safety, activity, and efficacy. Patients in good general condition and not heavily pretreated are those more likely to derive benefit from the targeted treatment.

•

Encorafenib plus cetuximab ± binimetinib is safe and effective for BRAF V600E mut mCRC even in the real-world setting.

•

Median OS is slightly shorter than in the BEACON trial, probably due to less selected patients in real life.

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Patients deriving more benefit from targeted therapy are likely those in good general conditions and not heavily pretreated.

•

BRAF adjusted MAF is worth further investigation to better characterize the genomic heterogeneity of BRAF V600E mut mCRC.

Can Natural Products be Used to Overcome the Limitations of Colorectal Cancer Immunotherapy?

Colorectal cancer (CRC) is a common cancer of the digestive system that endangers human health. Immunotherapy is widely used in the treatment of patients with cancer. Some patients with dMMR/MSI-H CRC benefit from treatments that use immune checkpoint inhibitors, but most CRC patients are not sensitive to immunotherapy. Furthermore, internal resistance and immune escape lead to a reduced immunotherapy response. Therefore, the development of an effective combination therapy to improve the response rate to immunotherapy is a goal of cancer research. Natural products are potential candidates for comprehensive cancer treatments due to their wide range of immunomodulatory effects through multifactorial underlying mechanisms. In this review, we summarize the challenges in the treatment of CRC and assess the immunomodulatory effects of natural products and their active components. Our work suggests that natural products represent potential options for combined CRC immunotherapy.

Systematic review of randomised clinical trials and observational studies for patients with RAS wild-type or BRAFV600E-mutant metastatic and/or unresectable colorectal cancer

Approximately 8-10% of metastatic colorectal cancer (mCRC) tumours harbour BRAF^V600E mutations. Eleven randomised controlled trials (RCTs) and 24 non-RCTs were identified. Seven studies evaluated BRAF inhibitors. Single-agent BRAF inhibitors had minimal efficacy, whereas BRAF inhibitor plus anti-EGFR therapy improved outcomes. In BEACON CRC, overall survival (OS) was significantly longer for patients receiving encorafenib plus cetuximab ± binimetinib when compared with irinotecan/FOLFIRI plus cetuximab as second- and third-line therapy. Seven prospective non-RCTs reported worse OS and progression-free survival (PFS) for patients with BRAF^V600E-mutant vs BRAF wild-type mCRC. Eight RCTs reported that PFS and OS were generally shorter for patients with BRAF^V600E-mutant mCRC vs those with KRAS or RAS wild-type mCRC. Patients with BRAF^V600E-mutant mCRC have worse outcomes with conventional therapy vs patients with BRAF wild-type tumours. BRAF inhibitors in conjunction with anti-EGFR therapy improves outcomes for patients with BRAF^V600E-mutant mCRC vs conventional therapy or a BRAF inhibitor alone.

BRAFV600E mutant colorectal cancer cells mediate local immunosuppressive microenvironment through exosomal long noncoding RNAs

BACKGROUND

BRAF^V600E mutated colorectal cancer (CRC) is prone to peritoneal and distant lymph node metastasis and this correlates with a poor prognosis. The BRAF^V600E mutation is closely related to the formation of an immunosuppressive microenvironment. However, the correlation between BRAF^V600E mutation and changes in local immune microenvironment of CRC is not clear.

AIM

To explore the effect and mechanism of BRAF^V600E mutant on the immune microenvironment of CRC.

METHODS

Thirty patients with CRC were included in this study: 20 in a control group and 10 in a treatment group. The density of microvessels and microlymphatic vessels, and M2 subtype macrophages in tumor tissues were detected by immunohistochemistry. Screening and functional analysis of exosomal long noncoding RNAs (lncRNAs) were performed by transcriptomics. The proliferation and migration of human umbilical vein endothelial cells (HUVECs) and human lymphatic endothelial cells (HLECs) were detected by CCK-8 assay and scratch test, respectively. The tube-forming ability of endothelial cells was detected by tube formation assay. The macrophage subtypes were obtained by flow cytometry. The expression of vascular endothelial growth factor (VEGF)-A, basic fibroblast growth factor (bFGF), transforming growth factor (TGF)-β1, VEGF-C, claudin-5, occludin, zonula occludens (ZO)-1, fibroblast activation protein, and α-smooth muscle actin was assessed by western blot analysis. The levels of cytokines interleukin (IL)-6, TGF-β1, and VEGF were assessed by enzyme-linked immunosorbent assay.

RESULTS

BRAF^V600E mutation was positively correlated with the increase of preoperative serum carbohydrate antigen 19-9 (P < 0.05), and with poor tumor tissue differentiation in CRC (P < 0.01). Microvascular density and microlymphatic vessel density in BRAF^V600E mutant CRC tissues were higher than those in BRAF wild-type CRC (P < 0.05). The number of CD163⁺ M2 macrophages in BRAF^V600E mutant CRC tumor tissue was markedly increased (P < 0.05). Compared with exosomes from CRC cells with BRAF gene silencing, the expression of 13 lncRNAs and 192 mRNAs in the exosomes from BRAF^V600E mutant CRC cells was upregulated, and the expression of 22 lncRNAs and 236 mRNAs was downregulated (P < 0.05). The biological functions and signaling pathways predicted by differential lncRNA target genes and differential mRNAs were closely related to angiogenesis, tumor cell proliferation, differentiation, metabolism, and changes in the microenvironment. The proliferation, migration, and tube formation ability of HUVECs and HLECs induced by exosomes in the 1627 cell group (HT29 cells with BRAF gene silencing) was greatly reduced compared with the HT29 cell group (P < 0.05). Compared with the HT29 cell group, the expression levels of VEGF-A, bFGF, TGF-β1, and VEGF-C in the exosomes derived from 1627 cells were reduced. The expression of ZO-1 in HUVECs, and claudin-5, occludin, and ZO-1 in HLECs of the 1627 cell group was higher. Compared with the 1627 cell group, the exosomes of the HT29 cell group promoted the expression of CD163 in macrophages (P < 0.05). IL-6 secretion by macrophages in the HT29 cell group was markedly elevated (P < 0.05), whereas TGF-β1 was decreased (P < 0.05). The levels of IL-6, TGF-β1, and VEGF secreted by fibroblasts in the 1627 cell group decreased, compared with the HT29 cell group (P < 0.05).

CONCLUSION

BRAF^V600E mutant CRC cells can reach the tumor microenvironment by releasing exosomal lncRNAs, and induce the formation of an immunosuppressive microenvironment.

BRAF testing in metastatic colorectal carcinoma and novel, chemotherapy-free therapeutic options

In the past 25 years, treatment of metastatic colorectal cancer (mCRC) has undergone profound changes. The approval of newer chemotherapeutics such as irinotecan and oxaliplatin was followed in 2005 by the first targeted therapies, for example, monoclonal antibodies directed against the epidermal growth factor receptor (EGFR), as cetuximab and panitumumab, or the angiogenesis inhibitors bevacizumab, ramucirumab, and aflibercept. With the rapidly progressing molecular characterization of mCRC in the last 10 years and the classification of the disease in four consensus subtypes, further changes are emerging, which will promote, among other things, the introduction of protein-kinase inhibitors developed for specific molecular aberrations as well as immune checkpoint inhibitors into the treatment algorithm.Thorough molecular pathologic testing is indispensable today for guideline-compliant treatment of mCRC patients. In addition to RAS testing as a precondition for the therapy decision with regard to cetuximab and panitumumab, BRAF testing is of considerable relevance to allow decision making with regard to the newly approved chemotherapy-free combination of the BRAF inhibitor encorafenib and cetuximab in cases where a BRAF-V600E mutation is detected. Additional diagnostic tests should also include genome instability (microsatellite instability). Overall, more and more molecular alterations need to be investigated simultaneously, so that the use of focused next-generation sequencing is increasingly recommended.This overview describes the prognostic relevance of BRAF testing in the context of molecular pathologic diagnostics of mCRC, presents new treatment options for BRAF-mutated mCRC patients, and explains which modern DNA analytical and immunohistochemical methods are available to detect BRAF mutations in mCRC patients.

[BRAF-V600E testing in metastatic colorectal cancer and new, chemotherapy-free therapy options. German version]

In the past 25 years, treatment of metastatic colorectal cancer (mCRC) has undergone profound changes. The approval of newer chemotherapeutics such as irinotecan and oxaliplatin was followed in 2005 by the first targeted therapies, for example, monoclonal antibodies directed against the epidermal growth factor receptor (EGFR), as cetuximab and panitumumab, or the angiogenesis inhibitors bevacizumab, ramucirumab, and aflibercept. With the rapidly progressing molecular characterization of mCRC in the last 10 years and the classification of the disease in four consensus subtypes, further changes are emerging, which will promote, among other things, the introduction of protein-kinase inhibitors developed for specific molecular aberrations as well as immune checkpoint inhibitors into the treatment algorithm.Thorough molecular pathologic testing is indispensable today for guideline-compliant treatment of mCRC patients. In addition to RAS testing as a precondition for the therapy decision with regard to cetuximab and panitumumab, BRAF testing is of considerable relevance to allow decision making with regard to the newly approved chemotherapy-free combination of the BRAF inhibitor encorafenib and cetuximab in cases where a BRAF-V600E mutation is detected. Additional diagnostic tests should also include genome instability (microsatellite instability). Overall, more and more molecular alterations need to be investigated simultaneously, so that the use of focused next-generation sequencing is increasingly recommended.This overview describes the prognostic relevance of BRAF testing in the context of molecular pathologic diagnostics of mCRC, presents new treatment options for BRAF-mutated mCRC patients, and explains which modern DNA analytical and immunohistochemical methods are available to detect BRAF mutations in mCRC patients.

Enhancing Therapeutic Efficacy of Oncolytic Herpes Simplex Virus with MEK Inhibitor Trametinib in Some BRAF or KRAS-Mutated Colorectal or Lung Carcinoma Models

Oncolytic virus (OV) as a promising therapeutic agent can selectively infect and kill tumor cells with naturally inherited or engineered properties. Considering the limitations of OVs monotherapy, combination therapy has been widely explored. MEK inhibitor (MEKi) Trametinib is an FDA-approved kinase inhibitor indicated for the treatment of tumors with BRAF V600E or V600K mutations. In this study, the oncolytic activity in vitro and anti-tumor therapeutic efficacy in vivo when combined with oHSV and MEKi Trametinib were investigated. We found: (1) Treatment with MEKi Trametinib augmented oHSV oncolytic activity in BRAF V600E-mutated tumor cells. (2) Combination treatment with oHSV and MEKi Trametinib enhanced virus replication mediated by down-regulation of STAT1 and PKR expression or phosphorylation in BRAF V600E-mutated tumor cells as well as BRAF wt/KRAS-mutated tumor cells. (3) A remarkably synergistic therapeutic efficacy was shown in vivo for BRAF wt/KRAS-mutated tumor models, when a combination of oHSV including PD-1 blockade and MEK inhibition. Collectively, these data provide some new insights for clinical development of combination therapy with oncolytic virus, MEK inhibition, and checkpoint blockade for BRAF or KRAS-mutated tumors.

Tumor suppressor miR-193a-3p enhances efficacy of BRAF/MEK inhibitors in BRAF-mutated colorectal cancer

Patients with BRAF‐mutated colorectal cancer (CRC) have a poor prognosis despite recent therapeutic advances such as combination therapy with BRAF, MEK, and epidermal growth factor receptor (EGFR) inhibitors. To identify microRNAs (miRNAs) that can improve the efficacy of BRAF inhibitor dabrafenib (DAB) and MEK inhibitor trametinib (TRA), we screened 240 miRNAs in BRAF‐mutated CRC cells and identified five candidate miRNAs. Overexpression of miR‐193a‐3p, one of the five screened miRNAs, in CRC cells inhibited cell proliferation by inducing apoptosis. Reverse‐phase protein array analysis revealed that proteins with altered phosphorylation induced by miR‐193a‐3p were involved in several oncogenic pathways including MAPK‐related pathways. Furthermore, overexpression of miR‐193a‐3p in BRAF‐mutated cells enhanced the efficacy of DAB and TRA through inhibiting reactivation of MAPK signaling and inducing inhibition of Mcl1. Inhibition of Mcl1 by siRNA or by Mcl1 inhibitor increased the antiproliferative effect of combination therapy with DAB, TRA, and anti‐EGFR antibody cetuximab. Collectively, our study demonstrated the possibility that miR‐193a‐3p acts as a tumor suppressor through regulating multiple proteins involved in oncogenesis and affects cellular sensitivity to MAPK‐related pathway inhibitors such as BRAF inhibitors, MEK inhibitors, and/or anti‐EGFR antibodies. Addition of miR‐193a‐3p and/or modulation of proteins involved in the miR‐193a‐3p–mediated pathway, such as Mcl1, to EGFR/BRAF/MEK inhibition may be a potential therapeutic strategy against BRAF‐mutated CRC.

BRAF Mutation as a Potential Therapeutic Target for Checkpoint Inhibitors: A Comprehensive Analysis of Immune Microenvironment in BRAF Mutated Colon Cancer

BRAF mutated colon cancer presents with poor survival, and the treatment strategies are controversial. The tumor microenvironment, which plays a key role in tumorigenesis as well as responses to treatments, of this subtype is largely unknown. In the present study, we analyzed the differences of immune microenvironments between BRAF mutated and BRAF wild-type colon cancer utilizing datasets from The Cancer Genome Atlas and Gene Expression Omnibus and confirmed the findings by tissue specimens of patients. We found that BRAF mutated colon cancer had more stromal cells, more immune cell infiltration, and lower tumor purity. Many immunotherapeutic targets, including PD-1, PD-L1, CTLA-4, LAG-3, and TIM-3, were highly expressed in BRAF mutated patients. BRAF mutation was also correlated with higher proportions of neutrophils and macrophages M1, and lower proportions of plasma cells, dendritic cells resting, and T cells CD4 naïve. In conclusion, our study demonstrates a different pattern of the immune microenvironment in BRAF mutated colon cancer and provides insights into the future use of checkpoint inhibitors in this subgroup of patients.

Beyond Microsatellite Instability: Evolving Strategies Integrating Immunotherapy for Microsatellite Stable Colorectal Cancer

OPINION STATEMENT

Advanced colorectal cancer (CRC) is a heterogeneous disease, characterized by several subtypes with distinctive genetic and epigenetic patterns. During the last years, immune checkpoint inhibitors (ICIs) have revamped the standard of care of several tumors such as non-small cell lung cancer and melanoma, highlighting the role of immune cells in tumor microenvironment (TME) and their impact on cancer progression and treatment efficacy. An "immunoscore," based on the percentage of two lymphocyte populations both at tumor core and invasive margin, has been shown to improve prediction of treatment outcome when added to UICC-TNM classification. To date, pembrolizumab, an anti-programmed death protein 1 (PD1) inhibitor, has gained approval as first-line therapy for mismatch-repair-deficient (dMMR) and microsatellite instability-high (MSI-H) advanced CRC. On the other hand, no reports of efficacy have been presented in mismatch-repair-proficient (pMMR) and microsatellite instability-low (MSI-L) or microsatellite stable (MSS) CRC. This group includes roughly 95% of all advanced CRC, and standard chemotherapy, in addition to anti-EGFR or anti-angiogenesis drugs, still represents first treatment choice. Hopefully, deeper understanding of CRC immune landscape and of the impact of specific genetic and epigenetic alterations on tumor immunogenicity might lead to the development of new drug combination strategies to overcome ICIs resistance in pMMR CRC, thus paving the way for immunotherapy even in this subgroup.

UGT1A1 Polymorphism for Irinotecan Dose Escalation in Patients with BRAF-Mutated Metastatic Colorectal Cancer Treated with First-Line Bevacizumab and FOLFIRI

Background

Patients with metastatic colorectal cancer (mCRC) and BRAF V600E mutation have a poor prognosis, with a median progression-free survival (PFS) of only 5–7 months after initial therapy. The current standard first-line chemotherapy for these patients includes FOLFOX or FOLFIRI plus bevacizumab. In this study, we explored the effects and oncological outcomes of UGT1A1 polymorphism for irinotecan escalation in patients with BRAF-mutated mCRC. Patients and Methods. This retrospective study included 17 patients with BRAF-mutated mCRC between April 2016 and December 2019. UGT1A1 genotyping was performed on all patients prior to initiating bevacizumab plus FOLFIRI chemotherapy. The primary endpoint was PFS, and the secondary endpoints were toxicity, response rate, disease control rate, and overall survival (OS).

Results

Fifteen and two patients had UGT1A1 1∗/1∗ and 1∗/28∗, respectively. Eight underwent irinotecan dose escalation with tolerable adverse effects (AEs), and nine maintained an irinotecan dose of 180 mg/m² or required deescalation to 150 mg/m² due to intolerable AEs. After a median follow-up period of 15.7 (range, 3–54) months, the median PFS and OS were 9.4 and 15.7 months, respectively. Grade 3/4 AEs were observed in three (6%) patients. The disease control and partial response rates were 64.7% and 11.8%, respectively, indicating that most patients (14, 82.3%) could maintain this as a first-line line therapy with stable disease or proceed to second-line therapy if disease progression occurred, thereby maintaining acceptable performance status.

Conclusions

The oncological outcomes of patients with BRAF-mutated mCRC treated using FOLFIRI plus bevacizumab with irinotecan dose escalation as a first-line therapy are acceptable with tolerable AEs; this may be a feasible treatment option in such patients. Pretherapeutic UGT1A1 genotyping-guided dose adjustment can achieve favorable outcomes.

A review of the sensitivity of metastatic colorectal cancer patients with deficient mismatch repair to standard-of-care chemotherapy and monoclonal antibodies, with recommendations for future research

In 5% of metastatic colorectal cancer (mCRC) patients, tumours display a deficient mismatch repair (dMMR) system. Immunotherapy is beneficial in dMMR mCRC patients and has recently been approved by the Food and Drug Administration for patients with unresectable or metastatic dMMR CRC. Although dMMR and proficient MMR (pMMR) CRC tumours are biologically distinct, they are commonly treated with the same chemotherapy and monoclonal antibodies. This includes dMMR mCRC patients who did not respond to immunotherapy (20-30%). However, it is unclear if these treatments are equally beneficial in dMMR mCRC. Of note, dMMR mCRC patients have a worse prognosis compared to pMMR, which may in part be caused by a lower response to treatment. To avoid unnecessary exposure to ineffective treatments and their associated toxicity, it is important to identify which systemic treatments are most beneficial in dMMR mCRC patients, thus improving their outcome. Indeed, future treatment strategies are likely to involve combinations of immunotherapy, chemotherapy and monoclonal antibodies. In this evidence-based review, we summarize clinical trials reporting treatment efficacy of different types of chemotherapy and monoclonal antibodies in dMMR mCRC patients. We also review the biological rationale behind a potential differential benefit of chemotherapy with or without monoclonal antibodies in dMMR mCRC patients. A barrier in the interpretation of preclinical results is the choice of model systems. They largely comprise traditional models, including cell lines and xenografts, rather than more representative models, such as patient-derived organoids. We provide concrete recommendations for clinical investigators and fundamental researchers to accelerate research regarding which systemic therapy is most effective in dMMR mCRC patients.

An update on the use of immunotherapy in patients with colorectal cancer

Introduction: Colorectal cancer (CRC) is the third most common malignancy worldwide, with recent trends demonstrating increasing incidence amongst younger patients. Despite multiple treatment options, metastatic disease remains incurable. A new therapeutic strategy to harness the host immune system, specifically with immune checkpoint inhibitors, now has reported results from a number of clinical trials. Areas covered: This review will discuss in detail microsatellite instability (MSI) and other biomarkers for response to immunotherapy, summarize the pivotal clinical trials of immune checkpoint inhibitors in early-stage and metastatic MSI colorectal cancer, explore strategies to induce treatment responses in MSS CRC and highlight the emerging treatments and novel immune-based therapies under investigation. Expert opinion: Immunotherapy is now a standard of care for the proportion of CRC patients with MSI. While overall survival data are still awaited, the promise of profound and durable responses is highly anticipated. The lack of efficacy in MSS CRC is disappointing and strategies to convert these 'cold' tumors are needed. Further elucidation of optimal use of treatment sequences, combinations and novel agents will improve outcomes.

Trends in Primary Surgical Resection and Chemotherapy for Metastatic Colorectal Cancer, 2000-2016

BACKGROUND

When, whether, and in whom primary tumor resection (PTR) for patients with metastatic colorectal cancer (CRC) is indicated remains unknown. With advances in multiagent systemic chemotherapy, PTR may be undertaken less frequently. The aim of this study was to obtain estimates of changes in the utilization of PTR and chemotherapy for metastatic CRC.

METHODS

Patients diagnosed with metastatic CRC between 2000 and 2016 were identified from Surveillance Epidemiology, and End Results (SEER) registry. Multivariable logistic regression defined odds of undergoing PTR. The analysis was also stratified by primary site (colon vs. rectum), age (younger than 50 vs. 50 y and older), and whether patients also underwent resection of metastatic sites (yes vs. no). The secondary endpoint of interest was the receipt of any chemotherapy, also assessed by multivariable logistic regression.

RESULTS

Among 99,835 patients with metastatic CRC, 55,527 (55.7%) underwent PTR. The odds of undergoing PTR decreased with a later year of diagnosis, with patients diagnosed in 2016 being 61.1% less likely to undergo surgery than those diagnosed in 2000 (adjusted odds ratio=0.39, 95% confidence interval: 0.36-0.42, P<0.0001; absolute percentage: 62.3% to 43.8%). Similar trends by year for PTR were observed among each of the subgroups, although patients with colon primary, young adults (age younger than 50 y), and patients also undergoing metastasectomy were more likely to undergo PTR (P<0.001 for all). In contrast, the odds of receiving chemotherapy increased dramatically with a later year of diagnosis (adjusted odds ratio=2.21, 95% confidence interval: 2.04-2.40, P<0.0001).

CONCLUSIONS

From 2000 to 2016, there was a sharp decline in the rate of PTR for patients with metastatic CRC, while the use of chemotherapy increased over the same period. Prospective studies are needed to define the optimal local treatment for patients with metastatic CRC.

RAS as a positive predictive biomarker: focus on lung and colorectal cancer patients

Rat sarcoma (RAS) oncogenes have intensively been investigated during the last decades. Taking into account all human tumours, Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) gene is the most frequently mutated (about 22%) among the three isoforms, followed by Neuroblastoma RAS Viral Oncogene Homolog (NRAS) (8%) and Harvey Rat Sarcoma Viral Oncogene Homolog (HRAS) (3%). In the last years, careful attention has been paid on KRAS and NRAS gene mutations in non-small-cell lung cancer (NSCLC) and colorectal cancer (CRC) patients because of their prognostic and predictive roles. In particular, a large body of literature data has been generated investigating clinical outcomes of targeted treatments in NSCLC and CRC KRAS- and NRAS-mutated patients. The latest evidences are here reviewed, providing also an overview of the real-world RAS mutation testing practice across different Italian laboratories. On this basis, we propose a knowledge-based system, www.rasatlas.com, to support the healthcare personnel in the management of patients featuring RAS gene mutations in the landscape of precision oncology.

Biomarker testing and mutation prevalence in metastatic colorectal cancer patients in five European countries using a large oncology database

Background: The literature on biomarker testing for metastatic colorectal cancer (mCRC) in Europe is scarce. This study aimed to estimate the percentage of mCRC patients from five European countries tested for biomarkers over time. Materials & methods: An oncology database was retrospectively analyzed; evaluated biomarkers were RAS, BRAF and microsatellite instability (MSI). The patients were drug treated during 2018 and tested for relevant biomarkers in 2013-2018. Results: RAS testing was conducted in >90% of mCRC patients from 2014 onwards. BRAF testing increased from 31% of mCRC patients in 2013 to 67% in 2018. MSI testing increased from 10 to 41%. There was no notable trend over time for RAS and BRAF mutation or MSI-high prevalence. Conclusion: Biomarker testing among patients diagnosed with mCRC was increased over time. This study demonstrates the quick uptake of biomarker testing in clinical practice. These findings are significant as biomarker-based drugs are becoming more common.

The Evolutionary Landscape of Treatment for BRAFV600E Mutant Metastatic Colorectal Cancer

The BRAFV600E mutation is found in 8-10% of metastatic colorectal cancer (mCRC) patients and it is recognized as a poor prognostic factor with a median overall survival inferior to 20 months. At present, besides immune checkpoint inhibitors (CPIs) for those tumors with concomitant MSI-H status, recommended treatment options include cytotoxic chemotherapy + anti-VEGF in the first line setting, and a combination of EGFR and a BRAF inhibitor (cetuximab plus encorafenib) in second line. However, even with the latter targeted approach, acquired resistance limits the possibility of more than an incremental benefit and survival is still dismal. In this review, we discuss current treatment options for this subset of patients and perform a systematic review of ongoing clinical trials. Overall, we identified six emerging strategies: targeting MAPK pathway (monotherapy or combinations), targeting MAPK pathway combined with cytotoxic agents, intensive cytotoxic regimen combinations, targeted agents combined with CPIs, oxidative stress induction, and cytotoxic agents combined with antiangiogenic drugs and CPIs. In the future, the integration of new therapeutic strategies targeting key players in the BRAFV600E oncogenic pathways with current treatment approach based on cytotoxic chemotherapy and surgery is likely to redefine the treatment landscape of these CRC patients.

New advances in the clinical management of RAS and BRAF mutant colorectal cancer patients

INTRODUCTION

In colorectal carcinogenesis, genetic alterations in RAS and BRAF oncogenes play an important role for cancer initiation and/or progression and represent a key focus in the search for targeted therapies. Despite many years of research and a great amount of studies, until very recently this pathway was considered extremely hard to downregulate to obtain a significant clinical impact in colorectal cancer patients. But better times are coming with the advent of new promising drugs and combinations strategies.

AREAS COVERED

In this review, we go over the biological characteristics of the MAPK pathway in colorectal tumors, while illustrating the clinical correlation of RAS and BRAF mutations, particularly its prognostic and predictive value. We also present newly data about recent improvements in the treatment strategy for patients harboring these types of tumors.

EXPERT COMMENTARY

With great advances in the knowledge of molecular basis of RAS and BRAF mutant colorectal cancer in conjunction with biotechnology development and the constant effort for improvement, in the near future many new therapeutic options would be available for the management of this group of patient with dismal prognosis.

BRAF Mutation in Colorectal Cancers: From Prognostic Marker to Targetable Mutation

Simple Summary

Colorectal cancer with a mutation in an oncogene BRAF has paid much attention, as it comprises a population with dismal prognosis since two decades ago. A series of research since then has successfully changed this malignancy to be treatable with specific treatment. Here we thoroughly overviewed the basic, translational and clinical studies on colorectal cancer with BRAF mutation from a physician’s viewpoint. Accumulating lines of evidence suggest that intervention of the trunk cellular growth signal transduction pathway, namely EGFR-RAS-RAF-MEK-ERK pathway, is a clue to controlling this disease. However, it is not so straightforward. Recent studies unveil the diverse and plastic nature of this signal transduction pathway. We will introduce our endeavor to conquer this condition, based on newly arriving datasets, and discuss how we could open the door to future development of CRC treatment.

Abstract

The Raf murine sarcoma viral oncogene homolog B (BRAF) mutation is detected in 8–12% of metastatic colorectal cancers (mCRCs) and is strongly correlated with poor prognosis. The recent success of the BEACON CRC study and the development of targeted therapy have led to the determination of BRAF-mutated mCRCs as an independent category. For nearly two decades, a growing body of evidence has established the significance of the BRAF mutation in the development of CRC. Herein, we overview both basic and clinical data relevant to BRAF-mutated CRC, mainly focusing on the development of treatment strategies. This review is organized into eight sections, including clinicopathological features, molecular features, prognosis, the predictive value of anti-epidermal growth factor receptor (EGFR) therapy, resistant mechanisms for BRAF-targeting treatment, the heterogeneity of the BRAF mutation, future perspectives, and conclusions. A characterization of the canonical mitogen-activated protein kinase (MAPK) pathway is essential for controlling this malignancy, and the optimal combination of multiple interventions for treatments remains a point of debate.

BRAF Alteration in Central and Peripheral Nervous System Tumors

BRAF (alternately referred to as v-raf murine sarcoma viral oncogene homolog B1) is a proto-oncogene involved in the mitogen-activated protein kinase (MAPK) pathway. BRAF alterations are most commonly missense mutations or aberrant fusions. These mutations are observed in numerous primary central nervous system tumors as well as metastases. This review discusses the prevalence of BRAF alteration within select notable CNS tumors, and their prognostic associations. Included are some novel entities such as diffuse leptomeningeal glioneuronal tumor (DLGNT), polymorphous low grade neuroepithelial tumor of the young (PLNTY), and multinodular and vacuolating neuronal tumor (MVNT). Knowledge of this gene’s integrity in CNS and PNS tumors can have profound diagnostic and therapeutic implications. Also reviewed are the current state of targeted therapy against aberrant BRAF as it pertains mostly to the CNS and to a lesser extent in PNS, and certain diagnostic aspects.

The treatment paradigm of right-sided metastatic colon cancer: harboring BRAF mutation makes the difference

PURPOSE

BRAF mutations represent the main negative prognostic factor for metastatic colorectal cancer and a supposed negative predictive factor of response to standard chemotherapy. We have explored survival difference in right-sided colon cancer (RCC) patients according to BRAF mutations, with the aim to identify any predictive factors of response to targeted-based therapy.

METHODS

A retrospective study of RCC patients, with BRAF known mutation status, treated with chemotherapy (CT) from October 2008 to June 2019 in 5 Italian centers, was conducted.

RESULTS

We identified 207 advanced RCC patients: 20.3% BRAF mutant and 79.7% BRAF wild type (wt). BRAF-mutant cancers were more likely to be pT4 (50.0% v 25.7%, p = 0.016), undifferentiated (71.4% v 44.0%, p = 0.004), KRAS wt (90.5% v 38.2%, p < 0.001), and MSI-H (41.7% v 16.2%, p = 0.019) tumors, with synchronous (52.4% v 31.5%, p = 0.018) and peritoneal metastases (38.1% v 22.4%, p = 0.003). Median overall survival (OS) was 16 v 27 months in BRAF mutant and BRAF wt (P = 0.020). In first-line setting, BRAF-mutant showed a 2ys OS of 80% in clinical trials, 32% in anti-VEGF, 14% in epidermial growth factor receptor (EGFR), and 0% in chemotherapy alone regimens (P = 0.009). BRAF-mutant patients demonstrated worse survival, regardless of targeted therapy administered. However, survival difference was statistically significant in the anti-EGFR-treated subgroup (16 v 28 months, P = 0.005 in BRAF mutant v BRAF wt, respectively).

CONCLUSIONS

Our study demonstrated that BRAF status makes the difference in treatment's outcome. Therefore, the anti-EGFR should not be excluded in all advanced RCC but considered on a case-by-case basis.

Resistance to anti-epidermal growth factor receptor in metastatic colorectal cancer: What does still need to be addressed?

Colorectal cancer (CRC) represents a global health problem, being one of the most diagnosed and aggressive tumors. Cetuximab and panitumumab monoclonal antibodies (mAbs) in combination with chemotherapy are an effective strategy for patients with RAS Wild Type (WT) metastatic colorectal cancer (mCRC). However, tumors are often unresponsive or develop resistance. In the last years, molecular alterations in principal oncogenes (RAS, BRAF, PI3KCA, PTEN) in the downstream pathway of the epidermal growth factor receptor (EGFR) and in other receptors (HER2, MET) that converge on MAPK-ERK signalling have been identified as novel mechanisms of resistance to anti-EGFR strategies. However, further efforts are needed to better stratify CRCs and ensure more individualized treatments. Herein, we describe the consolidated molecular drivers of resistance and the therapeutic strategies available so far, with an overview on potential biomarkers of response that could be integrated in clinical practice.

Comprehensive review of targeted therapy for colorectal cancer

Colorectal cancer (CRC) is among the most lethal and prevalent malignancies in the world and was responsible for nearly 881,000 cancer-related deaths in 2018. Surgery and chemotherapy have long been the first choices for cancer patients. However, the prognosis of CRC has never been satisfying, especially for patients with metastatic lesions. Targeted therapy is a new optional approach that has successfully prolonged overall survival for CRC patients. Following successes with the anti-EGFR (epidermal growth factor receptor) agent cetuximab and the anti-angiogenesis agent bevacizumab, new agents blocking different critical pathways as well as immune checkpoints are emerging at an unprecedented rate. Guidelines worldwide are currently updating the recommended targeted drugs on the basis of the increasing number of high-quality clinical trials. This review provides an overview of existing CRC-targeted agents and their underlying mechanisms, as well as a discussion of their limitations and future trends.